I’ve gone back to SE RCA’ed designs, but my heart lingers for that balanced purest design.Single-ended circuits tend to feature the 2nd harmonic as their primary distortion component.
Balanced circuits, because they cancel even-ordered harmonics, tend to feature the 3rd harmonic as their primary distortion component.
The ear treats the 2nd and 3rd about the same- they add to 'lushness".
But circuits that have the 3rd as their main distortion component overall tend to have considerably less distortion- and this continues into the higher ordered harmonics. They don't just have less of the even orders, they have less of the odd orders too. That 3rd harmonic is at a level that is often 1/10th of the level of 2nd you see in single-ended circuits.
So **generally** speaking, balanced circuits tend to be overall lower distortion and because the ear treats all forms of distortion as some sort of tonality (often favoring that tonality over actual frequency response) balanced circuits tend to sound more neutral- more transparent and more musical overall.